Device for opening or closing latched needles of a knitting machine

ABSTRACT

A knitting machine having needles with pivotal latches which are opened or closed by magnetic means having a surface adjacent the tips of the pivotal latches so that the latches are progressively opened and closed when there is relative movement between the needles and the magnetic means. The surface of the magnetic means corresponds substantially with the line followed by the tip of the latch as it is opened or closed.

United States Patent [19] Schmidt et al.

[ Nov. 4, 1975 DEVICE FOR OPENING OR CLOSING LATCHED NEEDLES OF A KNI'I'I'ING MACHINE [75] Inventors: Techniker Gerhard Schmidt;

Antonius Vinnermann, both of Stuttgart; Rainer Bender, Echterdingen, all of Germany [73] Assignee: I Franz Morat GmbH, Stuttgart,

Germany [22] Filed: May 23, 1974 [21] Appl. N0.: 472,880

[30] Foreign Application Priority Data May 28, 1973 Germany 2327228 [52] US. Cl. 66/111- [51] Int. Cl. D0413 15/08 [58] Field of Search 66/111; 335/284 [56] References Cited UNITED STATES PATENTS Murphy et a1. 66/111 2,796,732 6/1957 Hauberg 66/111 2,966,784 1/1961 Burdett 66/14 X 2,997,866 8/1961 Ashe et a1 66/111 3,236,068 2/1966 McDonough 66/1 I l FOREIGN PATENTS OR APPLICATIONS 106,861 3/1899 Germany 66/111 Primary Examiner-Ronald Feldbaum [57] ABSTRACT A knitting machine having needles with pivotal latches which are opened or closed by magnetic means having a surface adjacent the tips of the pivotal latches so that the latches are progressively opened and closed when there is relative movement between the needles and the magnetic means. The surface of the magnetic means corresponds substantially with the line followed by the tip of the latch as it is opened or closed.

18 Claims, 10 Drawing Figures U.S. Patent Nov. 4, 1975 Sheet 1 of 4 3,916,650

Sheet 2 of 4 US. Patent 'Nov. 4, 1975 U.S. Patent Nov. 4, 1975 Sheet 3 of4 3,916,650

US. Patent Nov. 4, 1975 Sheet 4 of4 3,916,650

A C A If; 5

15 QXB DEVICE FOR OPENING OR CLOSING LATCHED NEEDLES OF A KNITTING MACHINE This invention relates to a device for opening or closing the latched needles of a knitting machine.

Known devices which include a magnetic pole surface to open or close the latched needle of a knitting machine have electromagnets or pennanent magnets which, depending on the type of knitting machine, are arranged on a movable sliding carriage or on a stationary part of the machine, so that either the magnetic pole surface is moved past the needle or the needle is moved past the magnetic pole surface and the latches are opened or closed by magnetic forces, see for example US-PS 2,997,866.

An important disadvantage of magnetic devices this type for opening or closing latches is that neither the geometric shape nor the spatial arrangement of the magnetic pole surfaces is suitable for opening or closing the latch with certainty. For this reason such devices have not had any practical success.

According to the invention there is provided a device for opening or closing the latched needles of a knitting machine, comprising a magnetic pole surface designed in accordance with a preselected curved track of the tips of the latches during the opening or closing movement.

In addition the surface of the magnetic pole may include a pole of increased magnetic pole strength in the region of the initial position of the needle latch, so that the magnetic forces at the initial position have a relatively high value and the forces of friction or inertia, which are greatest at the beginning of the opening or closing process, can be overcome with certainty.

In devices suitable for the usual circular or flat knitting machines, the surfaces of the magnetic poles preferably have the shape of a helical line or are of an elliptical form.

The surfaces of the magnetic poles may be conveniently designed as permanent magnets.

Finally, the surfaces of the magnetic poles are preferably so designed that they cannot come into contact with the needle latches even if the latter are in an incorrect position.

The invention will now be described in more detail by way of example with reference to the accompanying drawings, in which:

FIGS. 1 and 2 schematically show the relevant part of a flat or circular knitting machine;

FIG. 3 shows a latched needle, with the latch open to different degrees, and the curved path described by the tip of the latch during opening with a linear movement of the latched needle;

FIG. 4 shows the latched needle of a circular knitting machine with the latch open to different degrees, and the curved path of the tip of the latch with a nonlinear movement of the latched needle;

FIG. 5 is a perspective view of a permanent magnet with a magnetic pole surface embodying the invention in which it is possible to see the positions of the needle latch relative to the surface of the magnetic pole during an opening process;

FIGS. 6 and 7 are a side view and plan view of the permanent magnet of FIG. 5;

FIG. 8 shows the relative positions of the needle latches with respect to a multiplicity of magnetic polar surfaces during an opening process; and

FIGS. 9 and 10 illustrate the manufacture of the magnetic pole surfaces.

Flat knitting machines (FIG. 1) include at least one needle bed 1 which has grooves running at right angles to its longitudinal direction within which latched needles 2 are arranged so as to be able to move up and down. The up and down movement of the latched needles'2 takes place under the control of needle cams 3, which include guides, (not shown) which operate in conjunction with butts of the needles. The needle cams 3 are attached to a sliding carriage 4, which is moved to and fro above the needle bed 1 in a direction at right angles to the length of the needles. Circular knitting machines (FIG. 2) include a fixed or rotatable needle cylinder 5 with grooves 6, within which, once again, latched needles 2 are mounted in bearings so as to move up and down, the butts of the needles being influenced by needle cams which are attached to a fixed or rotatable cam box ring surrounding the needle cylinder 5. A device 8, by means of which the latches of the needles 2 are opened can be arranged in conjunction with either type of knitting machine and mounted on either the sliding carriage 4 or the cam box ring.

FIG. 3 illustrates the latched needles 2 of knitting machines of these types in various positions. In the position a, the latch 13 has been pivoted so far about its centre of rotation 15 that it closes the needle hook 17 completely and thus makes the smallest possible angle B with the shank of the needle. In the positions b and c the latch 13 makes an angle B or B respectively with the shank of the needle, so that the needle is partially opened. In the position d the full opening of the needle has in fact been reached with the angle B where the angle B corresponds either to the position of widest opening on constructional grounds or to an angle of opening desired for knitting purposes, for instance The transition from state a to state d can take place in various ways. Where a flat knitting machine or a circular knitting machine with a needle cylinder in a fixed position is concerned, the tips of the latches 13 move on a circular path 19 (FIG. 3) with the needles 2 at rest, the centre point of the circular path being the centre of rotation 15. If, on the other hand, the needles perform a linear movement, in the direction at right angles to that in which they extend, during the opening and closing process (e.g. in the direction of the arrow P in FIG. 3) then the circular movement of the tips of the latches will be superimposed on a linear movement, so that, as a whole, the tips of the latches follow a curved track 21 which lies on the surface of a cylinder, whose radius is equal to thelength of the latches. Finally, where the latched needles of a circular knitting machine with a rotating needle cylinder are concerned, the tips of the latches move, during opening and closing, on a curved track which lies in the surface of a toroid, whose radius corresponds, on the one hand to the radius of the needle cylinder and, on the other hand, to the length of the latches.

The curved track on which the tips of the latches move during opening and closing also depends on the manner in which the latches are opened and closed. If the pivoting of the latch takes place with a constant angular velocity dB/dt and the linear movement of the needles with a constant velocity, then the curved track of the tips of the latches corresponds to a helical line, while different angular velocities of the latches or of the needles may lead to numerous other curved tracks.

It is, however, common to all these curved tracks that they lie either in the surface of the cylinder referred to above or in the surface of the toroid. I

Finally, a case is illustrated in FIG. 4 where the needles have an additional superimposed movement in the direction in which they extend, which may for instance be caused by a needle cam of the knitting machine. In this case also, the curved track of the tips ofthe latches may easily be calculated.

In the embodiment to be described, the data discussed above are used to design the form of the surfaces of the magnetic poles which serve to open or close the latches in such a way that the tips of the are, preferably, also guided on such a curved track as is Y easily realisable technically. I

In the following a preferred embodiment is described which is suitable for flat or circular knitting machines. It is assumed here that the centres of rotation of the needles during the opening and closing processes are arranged on a straight line (as for fiat knitting machines or circular knitting machines with a fixed needle cylinder) or are moved along a straight line (for circular knitting machines with a rotating needle cylinder), and, for thecase of the circular knitting machine the approximation is also made that the small section of the needle circle within which the opening or-closing process takes place corresponds to a straight line. This approximation is possible for circular knitting machines since the diameter of the needle circle is generally significantly greater than the distance X (FIG. 3), which is, for example, one or two centimetres.

Referring to FIGS. 5 to 7, the device 8 includes a permanent magnet 23, generally in the form of a squared block with length s, one pole surface 25 of which is so designed that the latches 13 of needles 2 moved in the direction of the arrow P are gradually opened. Since, in accordance with the above assumptions, the geometric points in space where the tips of the latches are located during the opening movement lie in the surface of a cylinder whose axis coincides essentially with the curved track of the centres of rotation 15, the surface 25 of the pole, if the opening or closing process is to take place with constant angular velocity, will correspond to the inner surface of a partial section, in the form of a helical line, cut from the surface of the cylinder with a curvature over the distance X which is approximately equal to 125. Since, however, an exact helical line requires relatively high technical costs, the pole surface 25 is preferably designed to elliptical.

An ellipse is obtained by sectioning a cylinder at an angle between 0 and 90 to the cylinder axis, so that any ellipse obtained in this manner fulfills the requirements of a possible curved track whose points as a whole lie in the surface of the cylinder. The length of the curved elliptical track depends on the angle through which the latch is to be pivoted and on the linear path X through which the needle is to be displaced relative to the surface of the pole or the surface of the pole displaced relative to the needle, in order to bring about the complete opening or closing process.

The distance of the pole surface 25 from the needle 2 is so chosen that it is impossible for the pole surface to be contacted by the tip of the latch at any position, even if the needles 2 are brought up to the pole surface 25 in an already partly opened state or cannot be opened on account of bending or catching, or at least not completely opened. In other words, at any point within the path X the latches 13 can take up any arbitrary pivoted position without contacting the pole surface 25.

At the starting point of the needle 2 the pole surface 25 includes a pole 27, which serves to significantly increase the magnetic field at this point on the pole surface and thus to give the latch 13 the necessary acceleration to overcome the initial friction and inertia. In the remaining parts of the pole surface 25 the magnetic field strength may be lower, since it only has to produce a force to hold and to guide the latches which are steadily opening wider. I

Because of the special design of the pole surface 25, the latches 13 of theneedles 2, during their path from the pole 27 to the other end of the pole surface 25, are always newly directed so as to remain pointing at right angles to the surface of the pole and the magnetic lines of force run parallel to the direction in which the latches extend. By this means the latches are continuously held under control, and experience no additional acceleration or retardation in one or other direction of rotation. I i i The permanent magnet 23 can be used both with a circular knitting machine with a rotating needle cylinder, where it will be mounted in a fixed position, and with a flat knitting machine. In a flat knitting machine, the permanent magnet 23 is conveniently built into the sliding carriage and is thus moved above the needles at the height of the needle hooks by the to and fro movement of the said carriage. I-Iere, since the needles are essentially at rest, the tips of the latches perform only a circular movement. Nevertheless this introduces no difference with respect to the functioning of the opening process when the pole surface 25, as in FIG. 5, is moved in the directioin opposite to the arrow P. In this case, in fact, the pole 27 is first moved past the needles in their fixed position, thus initiating the opening process, while subsequently the elliptical surface of the pole moves past the needle latches and causes the points of the needles to be always set at right angles to it. Because of the curvature of the pole surface 25 the latches 13 are thus continually opened wider. A corresponding process can also take place with a circular knitting machine with a needle cylinder in a fixed posi-- tion and a rotatable cam box ring, if the permanent magnet 23 is attached to the cam box ring. In spite of different curved tracks for the tips of the latches, the surface 25 of the pole has a form which corresponds with the track of the tips of the latches in each of the three cases.

The closing process can be carried .out by means of the same permanent magnet 23 and the same pole surface 25, in that, either the permanent magnet is arranged in the reverse direction, or it is moved in the opposite direction relative to the needles. It would be convenient in this case for the pole 27 to be displaced to the opposite end of the pole surface 25, so that the closing process can also be initiated with certainty.

Various modifications can be made to the example described, Thus, for instance, if the permanent magnet 23 is to be suitable to open or close the latches of needles which move on a curved track as in FIG. 4, it would be preferable to provide one or more kinks in the pole surface 25. Further, it would be possible to bring about the forced rotation of the latches by the action of the pole surface 25 with different angular velocities dB/dt or with different angular accelerations, by

- ensuring that the-curvature of the polesurface 25 is sufficient to rotate thelatches from theirposition at B, into their position at B,;'('FIG. 5), or vice versa. In addi tion the polesurface 25 need not be continuous but may be designed as a pole surface 29 assembled from a multiplicity of small individual magnets. arranged next to'each other, which, as isshown in FIG-'8, are ar ranged with increasing degree of obliquity according-to the desired state .of opening of the latches. Finally, the pole surfaces 25 01:29 may also bei designed as pole shoes of electrorrlagnets instead of as permanent magnets 23. Approximate solutions for the surfacesof the poles aresalso possible. 1 '1,

In the following example of the manufacture of a pole surface it is assumed that the length of the latchesl 4.5 mm-and the air gap between the tips of the latches and the pole surface 'l =:O.5 mm, so that a distance fl 5 mm exists between the centres of rotation and the pole surface. Further weassume a closing angle [3 15 and,.a maximumopeningan'gle. B ,,;=.140,to be achieved in a path X=,--mm. s 4 I. v

For the manufacture of a, pole surfacesuitable for this example afinger milling c u tte r a diameter; of 2] 10 mm is used. The positioning angle 9, between the axis of the milling tool and the work piece, for example in the form of a squared block, as well as the length s of the work piece,:can be calculated from the quantities B and X.

According to FIG. 9, where the circle represents the working region of the finger milling tool and the shaded region represents the finished work piece to which this is applied, the projection length P, which depends on the angle [3,, [3 is first determined so that, the value of X being known, the angle of application 6 can be calculated from the equation, tan 6 P/X and the length s can be calculated from the equation cos 0 X/s, see FIG. 10.

A pole surface 25, milled in this way, is well suited to the opening or closing of the latches of the needles, but it is certainly necessary to take care that in the adjustment of the pole surface to the knitting machine the angle of application 0 is observed exactly, which, in this case, corresponds to the angle between the work piece and its direction of transport or to the angle between the work piece and the path of the centre of rotation t5.

If the latches of the needles are to be opened or closed at several positions within the knitting machine, it is convenient to give the same polarity to all the pole faces in order to avoid undesirable effects due to the residual magnetism remaining in the needles.

The device illustrated has the important advantage that the tips of the latches are permanently in direct proximity to the surface of the magnetic pole during a normal opening or closing process and are thus guided by the magnetic surface. If, on the contrary, the needles are brought up to the magnetic polar surface in an already partly opened state, the tips of the latches enter into the direct proximity of the surface of the magnetic pole at some point on their path and are then once again opened or closed from this point as in the normal case.

The device illustrated enables positive opening or closing of the needle while pivoting the latches through a preselected angle. This is achieved without high construction cost and with the use of relatively low magnetic field strengths.

We claim:

v 1. In a knitting machine comprising a movable needle bed, at least one knitting needle mounted thereon; a latch pivotally mounted on said needle, said latch having atip movable to an open position and a closed position with respect to said needle, said tip moving along a curved path when said latch is pivoted to one-of said positions; and magnetic-meansmounted on said ma-, chine in a fixed position and having-a' curved face adjacent said needle bed, the pathof ,saidtip and; the curved face of said magnetic-means having substantially .the same curvature, said facegmagneticany attracting and guiding said: latch'to one of said positions when said needle bed is moved past said magnetic means.

, 2. In a knitting machine comprising aneedle. bed mounting at leastone knitting needle;a latch pivotally mounted ons said needlefsaid latch having; a tip movable =to.an open position and a close'd'position with re-; spect to said needle; and .ni agnetic means movablepast said needle bedand havinga curved face adjacent said needle bed for magnetically attracting and guiding said latchto one-ofsaid. positions, said curved face including a leading portion located close. to said'tip in one of said positions;:a trailing portion-located close to said tip in said other; position; and further intermediate portions between said leading portion and-said trailing por:

, tion, said further portions including first portions successively increasingly spaced fromsaid needle and then successively decreasingly spaced from said needle when said magnetic means is moved past said needle bed in one direction whereby said leading portion initiates and said further intermediate portions and said trailing portion successively continue and terminate the pivoting of said latch, each of said further intermediate portions being located close to the tip of said latching positions of said latch between said open and closed positions.

3. Device for opening and closing a latch pivotally mounted on at least one latch needle, said latch having a tip movable to an open and a closed position, said latch needle being mounted on a needle bed, said device comprising: magnetic means having a curved face located adjacent said latch needle for magnetically attracting said pivotal latch, said curved face having a leading portion, a trailing portion and further intermediate portions between said leading and said trailing portions, said portions being arranged on a curve shaped so that said latch is magnetically and progressively guided and pivoted to one of said positions when said needle bed and said curved face are relatively moved in one direction with respect to each other.

4. In a knitting machine according to claim 1 wherein said curved face has the shape of a helix the axis of which is substantially parallel to the direction of the movement of said needle bed and lies in the axis of rotation of said latch.

5. In a knitting machine according to claim 1, wherein the radius of said helix is greater than the length of said latch.

6. In a knitting machine according to claim 1, wherein said curved face has the shape of an ellipse which lies in plane, said plane and the direction of movement of said needle bed forming an angle.

7. In a knitting machine according to claim 2, wherein said curved face has the shape of a helix the axis of which is substantially parallel to the direction of the movement of said magnetic means and lies in the axis of rotation of said latch.

8. In a knitting machine according to claim 2, wherein the radius of said helix is greater than the length of said latch.

9. In a knitting machine according to claim 2, wherein said curved face has the shape of an ellipse which lies in a plane, said plane and the direction of movement of said magnetic means forming an angle.

10. In a knitting machine according to claim 6, wherein said needle bed is a rotatable needle cylinder having a plurality of said knitting needles mounted thereon and wherein said plurality of said knitting needles are moved by said needle cylinder past said magnetic means for pivoting the latches of said needles to one of said positions.

11. In a knitting machine according to claim 9, wherein said knitting machine has a flat needle bed having a plurality of said knitting needles mounted thereon and further comprises a carriage for movement past said needle bed, said magnetic means being mounted on said carriage.

12. A device according to claim 3, wherein said portions of said face form a helix such that said latch is pivoted in one of said positions when said needle bed and said face execute relative motion in a direction parallel to the axis of said helix.

13. A device according to claim 3, wherein said portions of said curved face of said magnetic means lie on 8 an ellipsoidal curve such that said latch is pivoted to one of said positions when said needle bed and said curved face are relatively moved with respect to each other in a direction oblique to the plane of said ellipsoidal curve.

14. In a knitting machine according to claim 1, wherein the leading portion of said curved face with respect to said knitting needle has a greater magnetic field strength for initiating the pivotal motion of said latch than said other portions.

15. In a knitting machine according to claim 2, wherein the leading portion of said curved fact has a greater magnetic field strength than said other portions.

16. A device according to claim 3, wherein said leading portion of said curved face has a greater magnetic field strength for initiating the pivotal motion of said latch than said other portions.

17. In a knitting machine according to claim 4, wherein said curved face is composed of a plurality of spaced segmental face portions, said portions being spaced along a helical line.

18. In a knitting machine according to claim 6, wherein said curved face is composed of a plurality of spaced segmental face portions, said portions being spaced along an ellipsoidal line. 

1. In a knitting machine comprising a movable needle bed, at least one knitting needle mounted thereon; a latch pivotally mounted on said needle, said latch having a tip movable to an open position and a closed position with respect to said needle, said tip moving along a curved path when said latch is pivoted to one of said positions; and magnetic means mounted on said machine in a fixed position and having a curved face adjacent said needle bed, the path of said tip and the curved face of said magnetic means having substantially the same curvature, said face magnetically attracting and guiding said latch to one of said positions when said needle bed is moved past said magnetic means.
 2. In a knitting machine comprising a needle bed mounting at least one knitting needle; a latch pivotally mounted on said needle, said latch having a tip movable to an open position and a closed position with respect to said needle; and magnetic means movable past said needle bed and having a curved face adjacent said needle bed for magnetically attracting and guiding said latch to one of said positions, said curved face including a leading portion located close tO said tip in one of said positions; a trailing portion located close to said tip in said other position; and further intermediate portions between said leading portion and said trailing portion, said further portions including first portions successively increasingly spaced from said needle and then successively decreasingly spaced from said needle when said magnetic means is moved past said needle bed in one direction whereby said leading portion initiates and said further intermediate portions and said trailing portion successively continue and terminate the pivoting of said latch, each of said further intermediate portions being located close to the tip of said latching positions of said latch between said open and closed positions.
 3. Device for opening and closing a latch pivotally mounted on at least one latch needle, said latch having a tip movable to an open and a closed position, said latch needle being mounted on a needle bed, said device comprising: magnetic means having a curved face located adjacent said latch needle for magnetically attracting said pivotal latch, said curved face having a leading portion, a trailing portion and further intermediate portions between said leading and said trailing portions, said portions being arranged on a curve shaped so that said latch is magnetically and progressively guided and pivoted to one of said positions when said needle bed and said curved face are relatively moved in one direction with respect to each other.
 4. In a knitting machine according to claim 1 wherein said curved face has the shape of a helix the axis of which is substantially parallel to the direction of the movement of said needle bed and lies in the axis of rotation of said latch.
 5. In a knitting machine according to claim 1, wherein the radius of said helix is greater than the length of said latch.
 6. In a knitting machine according to claim 1, wherein said curved face has the shape of an ellipse which lies in plane, said plane and the direction of movement of said needle bed forming an angle.
 7. In a knitting machine according to claim 2, wherein said curved face has the shape of a helix the axis of which is substantially parallel to the direction of the movement of said magnetic means and lies in the axis of rotation of said latch.
 8. In a knitting machine according to claim 2, wherein the radius of said helix is greater than the length of said latch.
 9. In a knitting machine according to claim 2, wherein said curved face has the shape of an ellipse which lies in a plane, said plane and the direction of movement of said magnetic means forming an angle.
 10. In a knitting machine according to claim 6, wherein said needle bed is a rotatable needle cylinder having a plurality of said knitting needles mounted thereon and wherein said plurality of said knitting needles are moved by said needle cylinder past said magnetic means for pivoting the latches of said needles to one of said positions.
 11. In a knitting machine according to claim 9, wherein said knitting machine has a flat needle bed having a plurality of said knitting needles mounted thereon and further comprises a carriage for movement past said needle bed, said magnetic means being mounted on said carriage.
 12. A device according to claim 3, wherein said portions of said face form a helix such that said latch is pivoted in one of said positions when said needle bed and said face execute relative motion in a direction parallel to the axis of said helix.
 13. A device according to claim 3, wherein said portions of said curved face of said magnetic means lie on an ellipsoidal curve such that said latch is pivoted to one of said positions when said needle bed and said curved face are relatively moved with respect to each other in a direction oblique to the plane of said ellipsoidal curve.
 14. In a knitting machine according to claim 1, wherein the leading portion of said curved face with respect to said knitting needle has a greater magnetic field strength for initIating the pivotal motion of said latch than said other portions.
 15. In a knitting machine according to claim 2, wherein the leading portion of said curved fact has a greater magnetic field strength than said other portions.
 16. A device according to claim 3, wherein said leading portion of said curved face has a greater magnetic field strength for initiating the pivotal motion of said latch than said other portions.
 17. In a knitting machine according to claim 4, wherein said curved face is composed of a plurality of spaced segmental face portions, said portions being spaced along a helical line.
 18. In a knitting machine according to claim 6, wherein said curved face is composed of a plurality of spaced segmental face portions, said portions being spaced along an ellipsoidal line. 